Why can't I get focus within a NSPanel when the "Title Bar" is set to not appear?

Question

If I create a project in Xcode 4.1, and set the MainMenu.xib to have two NSPanels, and put a NSTextField in both panels, if I set one of the NSPanels to not show the "Title Bar", then the textfield within that panel can not be clicked on or given focus.

Why??

Answer 1

A window (or a panel) without a titlebar cannot become key, so it can't get the focus. You have to subclass it and override its - (BOOL)canBecomeKey method, like this:

@interface MyPanel : NSPanel
@end

@implementation MyPanel

- (BOOL)canBecomeKeyWindow {
    return YES;
}

@end